This invention relates to decorative members of simple structure such a beads, welts or buttons welded under heat to the surface layer of a seat cushion. The present invention relates also to a method and apparatus for forming such welts or buttons.
Welts and buttons are frequently disposed on the seam portions of the surface layer of, for example, a seat cushion, so as to serve the purposes of reinforcement and accent or decoration.
FIGS. 1 and 2 show prior art examples of welts provided on the surface layer of a seat cushion. Referring to FIGS. 1 and 2, reference numerals 1, 1a and 1b designate surface layers of, for example, woven or non-woven fabric material, 2 designate filler pads of, for example, thin foamed polyurethane, and 3 designate backing layers. In FIGS. 1 and 2, the surface layers 1, 1a and 1b are shown disposed lowermost in view of the method welding which will be described later. A welt 4 shown in each of FIGS. 1 and 2 is composed of a core 4a and a covering 4b.
Referring to FIG. 1, the welt 4 (available in the market) is interposed between one surface layer 1a and the other surface layer 1b, and fixed in the seam between the layers 1a and 1b. Referring to FIG. 2, the core 4a is placed on the surface layer 1, and, after covering the core 4a with the covering 4b, the covering 4b is pressed onto the core 4a under application of heat as by high frequency heating to weld the welt 4 to the surface layer 1.
In the case of the prior art welt 4 shown in FIG. 1, the opposite ends of the covering 4b are overlapped and then sewn together, resulting in a large seam thickness. Further, the back end of the welt 4 protrudes considerably beyond the backing layer 3. Therefore, the prior art welt 4 shown in FIG. 1 has been defective in that it does not provide the feeling of comfortable sit when used in a seat cushion and, also, the protruding back end gives rise to an unsatisfactory finish when used in a seat cushion. The prior art welt 4 shown in FIG. 2 has also been defective in that exposure of excess portions 4c of the covering 4b on opposite sides of the welt 4 gives a non-beautiful external appearance.
FIGS. 3 and 4 show prior art examples of decorative buttons used as articles of accent on, for example, a seat cushion. Referring to FIG. 3, a seat cushion is composed of a stack of a surface layer 1 of, for example, woven or non-woven fabric material, a filled pad 2 of, for example, foamed polyurethane, a backing layer 3, and a plurality of wires 9 of spring steel disposed in contact with the backing layer 3. The backing layer 3 and spring wires 9 may not be provided depending on the type of seat cushions. A strip of suspension cloth 8 fixed at one end to a button 6 is passed through a slit 7 of the filler pad 2 and is pulled from the side of the backing layer 3 to form a recess in the surface of the surface layer 1, and the other end is then fixed to one of the spring wires 9 or any other suitable member.
In another prior art example shown in FIG. 4, a strip of suspension cloth 8 fixed at one end to a button 6 is pulled from the side of a backing layer 3 backing a filler pad 2 and is then fixed at the other end to an anchoring member 10 disposed between the filler pad 2 and the backing layer 3. Further, although not illustrated, there is a hook-and-eye combination in which a hook is pressed into an eye formed in a button.
It will thus be seen that the prior art buttons adapted to be attached to the surface layer of a seat cushion have been defective in that a plurality of individual buttons must be manually formed one after another, resulting in considerable man-hours leading to an undesirable increase in the costs. The prior art buttons have also been defective in that the otherwise beautiful appearance of a seat cushion is lost due to frequent come-off of one or more of the buttons, and repair of the seat cushion by reattachment of lost buttons will sometimes be quite difficult.